Fuel pump



Jan. 30, 1945. M. DACH 2,368,524

FUEL lPUMP Filed Sept. 17, 1942 INVENTOR J/lczoc ,DCL 07?/ JTNESSESPatented Jan. 30, 1945 UNETED STATES PATENT r OFFICE l 2,368,524 e IFUEL PUMP Max Dach, Flushing, N. Y. Application Septemberf17, 1942,ySerial No. 458,658v

` 2 claims. (ci. ros-20s) This invention relates to fuel pumps forinter,- na-l combustion engines,y and more particularly to animprovement therein which may be embodied in the conventional pump or inan attachment therefor.

' It is well known that fuel, such as gasoline, used for internalcombustion engines vaporizes readily and quite often vaporizationprevents the pump froml operating properly. Excess pressures forming inthe line prevent the pump from functioning eiciently, as does vaporaccumulating in the pump with no outletJ to escape. i Means have beenheretofore provided to relieve excessive v vapor pressures on thepressure side of the pump by meansof attachments. One of the purposes ofthis invention is to-relieve pressures and vaporization on both sides ofthe pump, and especially on the suction side of the pump Where theyoccur as often as on the pressure side.

In the present-day pump vapors are often trapped between the intake andoutlet Valves, and it is the purpose of this invention to provide a pumpin which the vapors will not be trapped within the pump but will ventthemselves through a relief valve o n one side and be transferred eitherto the carbureter bowl or returned to the tank, and on the other sidethe vaporsk may vent themselves through the carbureter needle valve.

An object of the invention is therefore to provide a pump in which theareas where vapors are apt to be trapped are so, constructed as to allowthe vapors to vent themselves automatically.

A further object is to provide a. more suitable valve which willincrease the'eiciency of the pump.

With these and other objects in View, which will become more apparent asthe description proceeds, reference is had to the accompanying drawing,in Which- Fig. l is a sectional velevation showing my invention embodiedWithin a more or less conventional fuel pump;

Fig. 2 is a sectional elevation showing my invention embodiedin anattachment for a conventional fuel pump.

Referring to Fig. l, the pump I is provided with the usual pump chamberII about a diaphragm I2, the outlet valve I3 and inlet valve i4 leadingfrom the filter bowl I5. These partsv operate in the customary manner,invwhich the diaphragm I2 on the down or suction stroke closes theoutlet valve, opens the intake valve, and draws fuel from the tank I5through the line II, passage I8, filter bowl I5, and the intake valveI4. 'The diaphragm I2 is operated by the rocker arm I9 engaging the camshaft 28. On the pressure stroke the pressure from the diaphragm I2closes the intake valve I4, opens the outlet valve I3, `and forces thefuel through the line 2| through the carbureter'22.

In the conventional pump diiculty has been experienced with vaporsrising from the lter` the passage I8 leading directly into the bowl andconstruct the head 32 of the bowl with an additional opening 33 leadingto the valve 34 positioned by the spring 35.` If the valve 34 is' madeof Neoprene, or other material which will not float in gasoline, thespring 35 is not necessary since the valve will automatically seatitself unless the vapor pressures are such as to open it. Above thevalve 34 is a restricted passage 36 which leads to the line 31 which maygo either to the i carbureter float chamber 38 or back to the tank.

While I have shown the valve 34 as a nat valve in Fig. l, a ball valve(as shown in Fig. 2) made of Neoprene or othersuitable substance, may beused.

It Will be noted that I have eliminated in the pump chamber I I theusual shoulder or boss contained in the conventionalpump, so that thebottom of the passage 21 leading to the outlet valve ls flush with thetop of the chamber to enable vapors which may form in the top of thechamber II to pass out through the outlet valve and to be vented by thecarbureter needle valve.

As the pump is operated, any vapors or builtup pressurein the area I8will pass upwardly through the opening 33, and if the fuel is heatedconsiderable pressure is built up to force open the valve 34 to allowthe vapors to pass through vthe pipe 31 back to the tank, or to thefloat chamber of the carbureter.` The valve 34 may be controlled so thatno more fuel can escape than the engine consumes at low speed and therestricted passage 36 will accomplish the same result. Whiletheoretically the pump on the suction stroke will cause the intake valveI4 to open and the relief valve 34 to close, and while on the pressurestroke it will cause the valve I4 to close, as a practical matter thereis a slight lag between the pressure and suction strokes and a periodduring which the intake valve remains open until the force of thepressure stroke is sufficient to close it. This sets up a slight backwash in the filter bowl I5, as the result of which there is a pointwhere a certain amount of pressure is exerted against the valve 34irrespective of whether or not pressure has been built up in the lterbowl by vapors. It follows, therefore, that the valve 34 will openslightly each time the pump changes or has a tendency to do so. In orderto insure this action, a slight hole may be drilled in the valve I4 tocreate an articial back wash.

In the attachment shown in Fig. 2, the housing 50 is provided to screwinto the end 5I of the fuel pump I connecting the passageway 53 with theline 54 from the gas tank. An opening 55 leads to the valve seat 56 anda spring-controlled valve 5l, which may be a Neoprene ball or a flatvalve, as shown in Fig. 1. An opening 58 is made between the passageway53 and the filter bowl I5 to allow vapors to pass into the passageway.

Beyond the valve 5'I is a chamber 50 closed by a plug 6I which has anopening B2 connecting with the line 63 leading to the float chamber ofthe carbureter or back to thetank. The plug 6I has depending walls 64forming a valve seat 65 at the lower end thereof. As vapors build uppressure in the line or in the filter bowl, the ball 5'I will be pushedupwardly against the seat 65 to allow said vapors to pass into thechamber 60. In the event no pressure is built up, this action will takeplace on the pressure stroke of the pump. Before the inlet valve I4 isclosed on the suction stroke of the pump, the ball 51 will be reseatedand the vapors allowed to pass through the passage 62 in the line 63.

It will be appreciated that the form shown in Fig. 2 is adaptable topumps now in use.

Where the operation of the intake valve is perfect and no back washoccurs in the change from the suction to the pressure stroke, the valveseat may be notched or a small passageway drilled in the pump to createa definite backwash within the lter bowl.

It will be appreciated that slight modications may be made in my deviceto accommodate it to various types of pumps without departing from myconceptive idea which includes the use of a relief valve to preventvapors forming in the suction end of the fuel line and to be operatedautomatically by the action of the pump, and that the pump chamber andlter bowl are so designed that rising vapors will not be trapped by thestructure of these elements and may find their way automatically to thepressure outlet valve and to the relief valve.

I claim:

1. The combination with a fuel pump having an inlet and an outlet valveand a filter bowl on'the suction side of said pump with a passageleading to said filter bowl from a feed line, of a supplemental valvebetween said filter bowl and said feed line communicating with saidpassage, said valve communicating with a line adapted to carry offvapors forming on the suction side of said pump.

2. A fuel pump comprising a pump chamber, a diaphragm in said chamber,and means for operating said diaphragm, an outlet valve, the bottom ofsaid outlet valve being on a level with the top of said chamber, aninlet valve, a lter bowl communicating with said inlet valve, a`passageleading from the fuel line into said filter bowl, asupplemental openingbetween said passage and said fuel bowl, and a relief valve positionedbetween said fuel line and said lter bowl.

MAX DACH.

